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Ask an Eye M.D. Answer Archive

Question:What is the difference between full-focus and full-focus multifocal IOLs and what are the drawbacks of ordinary full-focus IOLs? Also, are there any problems with full-focus accommodating IOLs? How long does it take for the ciliary muscles to adapt to the new lens?

Answer:"Full-focus" is a marketing term and not an optical term so the term is not useful. Multifocal IOLs help to focus at near, intermediate and distance, with the use of circular bands of correction throughout the optic of the lens. Ordinary IOLs focus at only one distance, so the patient will need to wear glasses for either near, distance, or both. Drawbacks to the multifocal are halo and glare at night (which often, but not always, gets better with time) and sometimes a loss in contrast — things appear a bit dimmer than usual. Pluses are good distances and near vision, but limited intermediate.

An accommodating IOL has an aspheric lens (like a good "ordinary" lens), which moves within the eye somewhat like our own lens did when we were younger — moving back and forth to focus near, intermediate and distance. It does best at distance and intermediate — in fact really excellent at these distances, but the near focus for reading a fine print book is not as predictable and readers are sometimes necessary. Some patients move the lens better with the ciliary muscle than others and there is no way to predict prior to the surgery. However, many patients get better and better at focusing up close even years after implantation.